To give oneself mighty airs: to assume, in manner, appearance, and tone, a superiority to which you have no claim, The same as Air, manner (q.v.).

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The plural is essential in this case to take it out of the category of mere eccentricity, or to distinguish it from air in the sense of deportment, as he had a fine, manly air, his air was that of a gentleman. Air, in the singular, being generally complimentary, but airs in the plural always conveying censure. In Italian, we find the phrase, Si da dell árie.